Polymers of carbon monoxide and olefinically unsaturated organic compounds, or polyketones, have been known and available in limited quantities for many years. For example, polymers of ethylene or ethylene-propylene which contain small quantities of carbon monoxide are disclosed in U.S. Pat. No. 2,495,286, prepared using free radical catalysts. British Pat. No. 1,081,304 discloses polymers containing higher concentrations of carbon monoxide prepared using alkylphosphine complexes of palladium salts as catalysts. A special class of linear polyketones is disclosed in U.S. Pat. No. 3,694,412, wherein the monomer units of carbon monoxide and olefinically unsaturated hydrocarbons occur in alternating order.
Polyketones are of considerable interest because they exhibit good physical properties. In particular, the high molecular weight linear alternating polymers have potential use as engineering thermoplastics due to their high strength, rigidity and impact resistance. These polymers can be represented by the general formula ##STR1## wherein A is the moiety obtained by polymerization of the olefinically unsaturated organic compound through the olefinic unsaturation. A general process for preparing such linear alternating polymers is disclosed, for example, in published European Patent Applications 121,965 and 181,014. The process comprises contacting the monomers in the presence of a catalyst obtained by reacting a compound of palladium, cobalt or nickel, the anion of a non-hydrohalogenic acid having a pKa less than about 2, and a bidentate ligand of phosphorus, arsenic or antimony. The resulting linear alternating polymers are generally high molecular weight thermoplastic polymers having utility in the production of articles for food and drink containers and for automobile parts. Although the properties of the polyketones are suitable for many applications, polyketones have the disadvantage of poor resistance to thermal oxidative degradation which limits their use in high temperature applications. For example, discoloration and decomposition take place when the polymers are exposed to elevated temperatures in the presence of air. The polymers crosslink, undergo chain scission, form undesirable degradation products, and rapidly lose attractive physical properties.
It is desirable to find compositions of polyketones that can withstand the thermal oxidative conditions encountered in higher temperature applications.